1. Field of the Invention
The present invention relates to a biplane X-ray diagnostic apparatus that makes it possible to perform simultaneous imaging in two directions.
2. Description of the Related Art
A biplane X-ray diagnostic apparatus, which has been developed mainly for inspection of the circulatory system, includes two X-ray imaging systems, namely, a frontal X-ray imaging system for imaging a patient from the front thereof and a lateral X-ray imaging system for imaging the patient from the side thereof, in order to make it possible to image the patient from two directions simultaneously. The frontal X-ray imaging system has an X-ray tube and an X-ray detector that are attached to both ends of a C arm supported by, for example, a stand placed on a floor. Similarly, the lateral X-ray imaging system has an X-ray tube and an X-ray detector that are attached to both ends of an Ω arm suspended from a ceiling.
Since the C arm of the frontal X-ray imaging system has the stand fixed to the floor, the C arm is capable of turning (pivoting) around the stand but, basically, cannot move on the floor. On the other hand the Ω arm of the lateral X-ray imaging system is suspended from sliders engaged with rails provided on the ceiling to be movable longitudinal and lateral along the rails. In radioscopy and imaging, the C arm and the Ω arm are initially aligned such that a region of interest of a patient is located in image centers in both the frontal X-ray imaging system and the lateral X-ray imaging system. In other words, the C arm and the Ω arm are aligned such that the region of interest of the patient is located on an imaging center axis of the frontal X-ray imaging system and located on an imaging center axis of the lateral X-ray imaging system.
Even if the region of interest is positioned on the respective imaging center axis, the region of interest does not always coincide with a rotation center point of the C arm and a rotation center point of the Ω arm. In this case, when the C arm or the Ω arm is rotated, the region of interest deviates from the respective imaging center axes. Consequently, since the region of interest deviates from the image centers, it is necessary to perform positioning of the region of interest again.